1. Field of the Invention
The present invention relates to a spin field effect transistor (FET), a magnetoresistive element and a spin memory.
2. Description of the Related Art
In recent years, research and development aiming at achievement of a spin electronics device using spin freedom of electron have been actively made. For example, devices using tunnel magneto-resistance (TMR) effect such as a magnetic random access memory (MRAM) and a reproduction magnetic head of a hard disk are typical examples.
Recently, the spin FET has been proposed as a next-generation spin device.
The spin FET has a feature in having a magnetic recording portion for memorizing binary data and is used as a component of a reconfigurable logic circuit. If a logic circuit is configured of the spin FET, all logics such as AND, NOR, OR and EX-OR can be achieved selectively only by rewriting data in a magnetic recording portion of one kind of circuit.
If this is achieved, necessity of changing the layout of a transistor depending on the kind of the logic circuit is eliminated, thereby achieving reduction of design/development term to a large extent and reduction of manufacturing cost to a large extent.
Therefore, it has been considered to use such a logic circuit by combination of a non-volatile semiconductor memory such as a magnetic random access memory and a ferroelectric random access memory (FeRAM).
However, in a current spin FET, writing of data into the magnetic recording portion is carried out with current magnetic field (magnetic field generated by a writing current) or a spin injection current (spin torque by a spin polarized electron).
Thus, if the device size is decreased when the current magnetic field is used in the former case, the value of write-in current is increased thereby increasing consumption power. If the spin injection current is used as the latter case, a problem in reliability, that is, destruction of a tunnel barrier film occurs because a large current density is needed for data writing.
Such a problem occurs also in the spin memory in which magnetization of the magnetoresistive element is changed using the spin freedom of electron.